1. ANDERSEN, A. C., and HART, G. H. (1943). Amer. J. vet. Res., 4, 307.
2. BIRCH-HIRSCHFELD, A. (1900). v. Graefes Arch. Ophthal., 50, 166.
3. Text-book of Ophthalmology,;DUKE-ELDER, S.,1932
4. EINARSON, L. (1951). Acta path. microbiol. scand., 28, 82.
5. HART, G. H., and GUILBERT, H. R. (1937). J. Amer. vet. med. Ass., 91 (44 new series), 193.